Nuclear Spin Relaxation Rate Near The Disorder-Driven Quantum Critical Point In Weyl Fermion Systems

Disorder such as impurities and dislocations in Weyl semimetals drives a quantum critical point (QCP) where the density of states at the Weyl point gains a nonzero value. Near the QCP, the asymptotic low-energy singularities of physical quantities are controlled by the critical exponents v and z. The nuclear spin-lattice relaxation rate, which originates from the hyperfine coupling between a nuclear spin and long-range orbital currents in Weyl fermion systems, shows intriguing critical behavior. Based on the self-consistent Born approximation for impurities, we study the nuclear spin-lattice relaxation rate 1/T-1 due to the orbital currents in disordered Weyl SMs. We find that (T1T)(-1)similar to E-2/z at the QCP where E is the maximum of temperature T and chemical potential mu(T) relative to the Weyl point. This scaling behavior of (T1T)(-1) is also confirmed by the self-consistent T-matrix approximation, where a remarkable temperature dependence of mu(T) could play an important role. We hope these results of (T1T)(-1) will serve as an impetus for exploration of the disorder-driven quantum criticality in Weyl materials.